I have a quite old software which doesn't support TLS 1.2. However SMTP Server only supports TLS 1.2.
Now I wanted to use stunnel to connect to SMTP server and and also listening for smtp access. I have already a valid certificate for this server. Before configuring different TLS versions I only wanted to test if this "stunnel proxy" works in general. I use Thunderbird to connect to :587
In [TLS_proxy_connector] and [TLS_proxy_listener] I have protocol = smtp
. I've tried to comment them out in one or both sections. However I get an immediate error or some kind of timeout and Thunderbird can't sent the E-Mail.
Here is the stunnel config:
setuid = stunnel4
setgid = stunnel4
foreground = yes
;don't write pid
pid =
[TLS_proxy_connector]
client = yes
accept = 127.0.0.1:53681
protocol = smtp
connect = <mailserver>:587
verify = 2
CApath = /etc/ssl/certs/
checkHost = <mailserver>
;OCSPaia = yes
[TLS_proxy_listener]
accept = 587
protocol = smtp
key = /etc/ssl/private/key.pem
cert = /etc/ssl/certs/cert_.pem
CAfile = /etc/ssl/certs/chain_.pem
connect = 53681
What am I doing wrong? Is there another tool which fits better here? I know I could setup an own mailserver which accepts TLS 1.0 and 1.1 and uses as smarthost, but that would be too much, because then I have to care about security. Currently checks security because you're only allowed to send with valid credentials. Thanks for your help.
Update: It works with above configuration when both entrys have protocol = smtp
. I'll add more info when further tests have been done regarding TLS versions.